The United States is condemning what it calls a "barbaric" reported attack by Syrian helicopters dropping barrel bombs on a camp for people displaced by the country's three-and-a-half-year war.

The Britain-based Syrian Observatory for Human Rights said the attack Wednesday in Idlib province killed at least 10 people.

U.S. State Department spokeswoman Jen Psaki said the U.S. could not immediately confirm details, but is "horrified" by the reports, and has consistently spoken out against the Syrian government's "callous disregard for human life."

Psaki also reiterated the need for Syria to be held responsible for acts against civilians during the conflict that began as peaceful protests in March 2011 before spiraling into a war that has killed nearly 200,000 people.

The fighting has forced more than 3 million refugees to flee to neighboring countries and displaced another 6.5 million within Syria.

A United Nations panel has issued periodic reports on the human rights situation in Syria during the war, consistently finding that government forces are carrying out widespread attacks on civilians.

The latest document, issued in August, describes a reliance on "heavily destructive firepower" and indiscriminate attacks that include the use of barrel bombs. It notes that such tactics paralyze and terrorize the civilian population, and amount to illegal acts under international humanitarian law.